Resection of the suprameatal tubercle in microvascular decompression for trigeminal neuralgia.

BACKGROUND: The suprameatal tubercle (SMT) may obscure the neurovascular compression (NVC) in microvascular decompression (MVD) for trigeminal neuralgia (TGN). The aim of this study is to address the necessity of resecting SMT in MVD for TGN. METHODS: We retrospectively analyzed radiological findings of 461 MVDs in patients with TGN, focusing on the relation between SMT and the NVC site. Three-dimensional (3D) images were used for preoperative evaluation. The NVC sites were obscured by SMT in 48 patients (10.4%) via the retrosigmoid approach. This study was conducted to review the management of SMT among these patients. Resection of SMT was performed in 8 patients (resected group) for direct visualization of the NVC site. On the other hand, nerve decompression was achieved without resecting SMT for the rest of the 40 patients (non-resected group). Biographical data, radiological findings, intraoperative findings, and surgical outcomes were retrospectively evaluated. RESULTS: The mean height of SMT obscuring NVC was 5.0 mm (2.8-13.9 mm) above the petrous surface. The NVC was located at a mean of 1.9 mm (0-5.9 mm) from the porous trigeminus. The most common offending vessel was the superior cerebellar artery (SCA, 56.3%), followed by the transverse pontine vein (TPV, 29.2%). In the resected group, the transposing culprit vessels were feasibly performed after direct visualization of the NVC site, whereas in the non-resected group, the SCA was successfully transposed using curved instruments after thorough dissection around the nerve. TPV having contact with the nerve was coagulated and divided. Immediate pain relief was obtained in all patients except one who experienced delayed pain relief 1 month after surgery. Facial numbness at discharge was noted in 9 patients (18.8%); thereafter, numbness diminished over time. Numbness at the final visit was observed in 5 patients (10.4%) at mean of 49 months after MVD. Recurrent pain occurred in 4 patients (8.3%) in total. Statistical analysis showed no significant differences in surgical outcomes between both groups. CONCLUSIONS: Direct visualization of the NVC site by resecting the SMT does not affect surgical outcomes in the immediate and long term. Resecting the SMT is not always necessary to accomplish nerve decompression in most cases by use of suitable instruments and techniques.

[Trigeminal neuralgia secondary to petrous endostosis]. / Neuralgia del trigémino secundaria a endostosis del hueso temporal.

Arterial neurovascular compression is hypothesised to be the main cause of primary trigeminal neuralgia. Although it is the most common cause, other pathologies, such as tumours in the cerebellopontine angle, can cause trigeminal pain. We report a case of a 44-year-old female patient with right trigeminal neuralgia without satisfactory response to medical treatment. Cerebral MRI showed no structural injuries. During microvascular decompression of the trigeminal nerve, endostosis of the internal aspect of the petrous bone was found to compress the trigeminal nerve. The pain disappeared completely in the early postsurgical period, after the complete drilling of the endostosis and microvascular decompression. The patient remains asymptomatic one year later. Endostosis of the petrous bone is a rare cause of trigeminal neuralgia. A proper review of preoperative studies would enable the definitive surgical approach to be optimised.

Suprameatal Extension of Retrosigmoid Approach in Microvascular Decompression for Trigeminal Neuralgia with Petrous Endostosis: Case Report and Literature Review.

Petrous endostosis or prominent suprameatal tubercle is a rare entity which may prevent adequate microscopic exposure of the trigeminal nerve root entry zone during microvascular decompression (MVD) for trigeminal neuralgia. We present a rare case of trigeminal neuralgia (TN) with petrous endostosis, which was managed adequately by partial removal of the prominent suprameatal tubercle to improve the obscured site of neurovascular conflict and enabled complete MVD. Through this manuscript, we additionally discuss the nuances involved in this extension of the standard retrosigmoid approach in light of the published literature. Petrous endostosis encountered during MVD for TN can impose an operative challenge. Suprameatal extension of the standard retrosigmoid approach improves exposure at the site of neurovascular conflict but requires utmost care and attention to avoid complications. We emphasize recognizing this anatomical variation in the preoperative period to predict an operative difficulty, ensure appropriate patient counselling, and avoiding surgical complications.